Chain (unit)
![Location designator painted on a British railway bridge, showing 112 miles and 63 chains; photograph taken August 2007](/Images/godic/202501/03/Bridge_miles_and_chains3910.jpg")
A chain (ch) is a unit of length. It measures 66 feet, or 22 yards, or 100 links, or 4 rods (20.1168 m). There are 10 chains in a furlong, and 80 chains in one statute mile. An acre is the area of 10 square chains (that is, an area of one chain by one furlong). The chain has been used for several centuries in Britain and in some other countries influenced by British practice.